Perception apparatus for the blind



y 1966 B. A. BENSON 3,250,023

PERCEPTION APPARATUS FOR THE BLIND Filed Feb. 13, 1964 1 SCANNING DISC (NIPKOW) FIG.1

PHOTO CELL BENGT ANDEES B[N50/V B 20W mam/1% A TTOPNEVS 3,250,023 PERCEPTION APPARATUS FOR THE BLIND Bengt Anders Benson, Styckjunkargatan 5, Stockholm, Sweden Filed Feb. 13, 1964, Ser. No. 344,587 4 Claims. c1. 3s-s5 The present invention relates to an apparatus intended to aid the blind in reading ordinary texts or printed matter in general, as drawings, etc. Many an apparatus of this type has been devised and suggested and there can be no doubt that such an apparatus would be of great help to the blind, especially in professional connections, provided it could be made of moderate size and complexity. Most earlier projects of this kind have been based on acoustic devices, i.e., the characters have been scanned in one way or other,prducing certain acoustic signals typical of the individual characters to be heard by the blind person. However, none of these devices has found any practical application of importance, owing in particular to their slow operation and uncertainty.

It is the purpose of the present invention to produce an apparatus by means of which a blind person will be able to read an ordinary printed or written text, follow up a drawing or circuit diagram, etc. The invention presupposes that the blind person can use his fingers as sense organs, means that the apparatus according to the invention is based on skin sensations.

It is well known that blind people using the tips of their fingers can at a considerable speed read writing or printing for the blind, i.e., a type of text in which the letters are represented by tangible dots combined into an alphabet according to the system invented by Braille. There has also been another, although less convenient, method of reading that was based on the blind individuals digital scanning of a text produced in relief print, i.e., with the characters raised by pressing some suitable material. As mentioned before, this method proved to be rather unpractical, especially owing to its inherent need for a material of considerable stiffness and strength, and the necessity of printing large size characters which made the text bulky.

The apparatus to be described below and its mode of operation are designed to produce by electrical means a pure contact sensation of the shape of the printed, etc., character on the readers finger tips. However, to produce sensations of this kind by electric means requires special measures to be taken. It is quite obvious that a subject will feel an electric current if some part of his body is exposed to it. On the other hand he will find it difficult to locate the point of contact, i.e., the point where the electrode touches his body. Suppose that a metal pin is fitted in an insulating surrounding material and that the surface is ground in such a way that the point of the pin becomes flush with the insulating material. Consequently, the pin will not be noticed when the tip of the finger is rubbed over the surface. Suppose, then, that an electric potential of moderate strength is applied to the pin.

Provided that the body is grounded the current will be noticed from prickly feelings in various parts of the finger tip, but it will still be impossible to locate the contact pin.

There are, however, electric currents with quite another elfect in a mechanical sense, viz., the high-tension, high-frequency, low energy Tesla currents, once very much in medical use though of doubtful value for that purpose. Owing to their extremely high frequency the Tesla currents are not capable of passing through the body tissues but follow the epidermis layer of the skin, and due to their almost negligible energy they have no heating action and cannot burn the skin. In fact, they produce a purse sensation of touch-+by connecting the above-mentioned pin in its insulating envelope to a source of weak Tesla current and rubbing the finger across the plane sur- I face one will experience the same sensation as from rubbing the. finger gently with a pinpoint.

The apparatus according to the present invention acts by scribing an enlarged character or similar sign on the readers finger tip (or tips) with the aid of a Tesla impulse. The apparatus will be described in certain detail below by way of example and with reference to the attached drawing, where FIG. 1 is a horizontal projection of the perforated scanning disk, a so-called Nipkow disk, forming part of the apparatus;

FIG. 2 is a diagrammatic transverse section through the said disk to illustrate the mode of cooperation between the vital parts of the apparatus; and

' FIG. 3 indicates how the letter A is shown in the picture gate of the apparatus.

Before describing the apparatus in detail a few basic facts deserve mentioning. First, the term Tesla current should not be understood in a too literal sense: in principle, it is suflicient if the current used fulfils the following requirements:

(1) The frequency of the current shall be so high that no significant migration of ions and, consequently, no

physiological effects (with the exception of pure touch sensations) occur.

(2) It shall be of so low energy that no significant heat effects ensue.

(3) The tension of the current shall be so high that without difiiculties, it will flash over to an object (human body) of zero, or almost zero, potential. It should not be necessary, however, to resort to the enormous voltages that may be obtained from the ordinary Tesla highfrequency transformer.

There is, rather obviously, still another requirement, viz., that it must be possible to produce the current in some type of controlled oscillation circuit.

The mechanical portion of the perception apparatus comprises a rotary scanning disk 1 as shown in FIGS. 1 and 2, the said disk comprising an outer [metal part 2 surrounding an inner part 3 of insulating material. The outer part contains a series of holes 4 arranged in spiral. A corresponding series of pegs 5 driven through the disk is arranged in another spiral immediately inside in the inner disk'part, each element in the latter spiral being arranged at angular displacement relative to the corresponding element in the outer spiral. The disk is covered by a hood (not illustrated) with two diametrically opposed openings 6 and 7, the former (6) being arranged below the disk underneath the outer spiral of holes whereas the latter (7) is arranged above the disk, forming a gate to the inner spiral of pegs 5. A small electric motor (not illustrated) is employed for rotating the scanning disk.

The basic principle underlying the Nipkow scanning disk is well known and should need no further explana tion. The block diagram, FIG. 2, is to illustrate the operation of the apparatus. The text to be read (or drawing, etc., to be scanned) is below opening 6, an enlarged image of the strongly illuminated characters, etc., being projected by an optical device 8 (most suitably one at a time) through the opening where the image is then scanned by means of the spiral of holes 4 in the ordinary way. The source of light for illuminating the text is marked 8a. A photo-cell unit 9, receiving the light pulses, sends signals through an amplifier 10 to a Tesla. generator 11 which is controlled by the said signals in such way as to be blocked while light is entering the photo cell and started when the flow of light ceases. From the generator the high-frequency current is led to an electrode 12 arranged immediately below the picture gate 7 and from thence through the peg 5 that is just passing the opening. The

user, holding his finger (which may be covered with a thin nylon finger-stall) in the opening, feels the character projected through opening 6 being scribed on an enlarged scale on his finger tip by an electrical pulse.

FIG. 3 shows how the pegs 5 fitted in the insulating disk 3 produce a character, here the letter A." In the above description the reader was said to hold his finger tip directly against the rotating disk, but as an alternative the picture gate 7 may be closed by a number of densely fitted conductive pegs insulated from each other, and making contact with the rotating disk. Thus, during its passage every peg 5 sweeping the gate 7 makes contact with a series of pegs fitted in the latter, which in their turn convey the signal to the finger. The practical and mechanical aspects of the manufacturing of the said apparatus are beyond the scope of the present invention and will not be discussed here. However, for obvious reasons it has to be a device of low weight that can be held and moved along the lines of text by the user.

The generator 11 is a most important component of the perception apparatus and has to fulfillcertain requirements. So, the operating oscillation circuit has to be fast, i.e., it must be capable of rapid changes between the inactive and the oscillating state. How rapid, naturally, depends on the speed of the sequence of images, i.e., the number of times the image is scribed in the picture gate 7 every second or, in other words, the number of disk rotations per second. The ordinary feed rate of cinema film, 24 exposures per second, is higher than actually required for this purpose, a rate of 12-16 exposures per second probably being more appropriate for all practical purposes. The design of the generator 1.1 should be based on the application of electronic pulse techniques.

It is well known that the Nipkow disk was widely used for scanning the image while television was still in its beginnings. However, owing to the following three main disadvantages the Nipkow, or mechanical, system was not satisfactory for that purpose: drawbacks related to synchronization, image shading, and image size. perception apparatus according to the present invention none of the disadvantages mentioned is of importance as (1) The transmitting and receiving disks are fitted on the same shaft, eliminating synchronization problems,

(2) The aim is only to distinguish between light and darkness, eliminating the difiiculties associated with shading the image, and

(3) The small size of the image is natural in a case like this.

As has been stated in the introduction the perception apparatus according to the present invention is intended With the to make it possible for the blind to read ordinary printed or written matter. The invention does not, however, presuppose'the apparatus to be employed for reading in general, as of books, etc., since the modern tape recorder will probably ofier more convenient help for that purpose. Realizing the great need for technical assistance to the blind in their work the perception apparatus according to the invention, making it possible for the blind to read drawings, check illustrations or find their way in handbooks, may become an aid of very great importance.

What I claim is:

1 Perception apparatus for the blind, comprising a re tatable scanning disk having a series of apertures therethrough arranged in a spiral and adapted to scan an image which is optically formed of indicia, a controlling and amplifying unit, a high frequency generator coupled to said controlling and amplifying unit, photosensitive means for receiving the light pulses from the scanning disk during the scanning operation and transmitting in response to the said pulses signals to said controlling and amplifying unit, which in turn controls in response to the said signals said high-frequency generator, a rotatable plate of insulating material fixed with respect to said scanning disk for rotation therewith and having a series of contact pegs embedded therein, said pegs having their points flush with the surface of the plate, the output of said generator being conducted to said pegs, said pegs being so oriented in the plate as to forn ia pattern corresponding to and moving in synchronism with the spiral of apertures in the scanning disk.

2. Perception apparatus in accordance with claim 1 wherein the high-frequency generator provides a low power, high tension output.

3. Perception apparatus in accordance with claim 1 wherein said scanning disk is annular and snugly surrounds said rotatable plate.

4'. Perception apparatus in accordance with claim 1 wherein said contact pegs are arranged in a spiral corresponding to but displaced angularly with respect to said apertures.

References (Iited by the Examiner UNITED STATES PATENTS 8/1933 Naumburg 3535.1 12/ 1947 Potter. 

1. PERCEPTION APPARATUS FOR THE BLIND, COMPRISING A ROTATABLE SCANNING DISK HAVING A SERIES OF APERTURES THERETHROUGH ARRANGED IN A SPIRAL AND ADATPED TO SCAN AN IMAGE WHICH IS OPTICALLY FORMED OF INDICIA, A CONTROLLING AND AMPLIFYING UNIT, A HIGH FREQUENCY GENERATOR COUPLED TO SAID CONTROLLING AND AMPLIFYING UNIT, PHOTOSENSITIVE MEANS FOR RECEIVING THE LIGHT PULSES FROM THE SCANNING DISK DURING THE SCANNING OPERATION AND TRANSMITTING IN RESPONSE TO THE SAID PULSES SIGNALS TO SAID CONTROLLING AND AMPLIFYING UNIT, WHICH IN TURN CONTROLS IN RESPONSE TO THE SAID SIGNAL SAID HIGH-FREQUENCY GENERATOR, A ROTATABLE PLATE OF INSULATING MATERIAL FIXED WITH RESPECT TO SAID SCANNING DISK FOR ROTATION THEREWITH AND HAVING A SERIES OF CONTACT PEGS EMBEDDED THEREIN, SAID PEGS HAVING THEIR POINTS FLUSH WITH THE SURFACE OF THE PLATE, THE OUTPUT OF SAID GENERATOR BEING CONDUCTED TO SAID PEGS, SAID PEGS BEING SO ORIENTED IN THE PLATE AS TO FORM A PATTERN CORRESPONDING TO AND MOVING IN SYNCHRONISM WITH THE SPIRAL OF APERTURES IN THE SCANNING DISK. 